The emphasis of this project is to use molecular genetics, including recombinant DNA techniques, to understand the pathogenesis of gonorrhea and some other infectious diseases. We have characterized one of the gonococcal R-plasmids by determining a physical map of many restriction endonuclease sites. While characterizing this plasmid, we also developed a method to specifically end-label DNA fragemens by using certina enzymes which make asymmetric cleavages of the DNA. We have made gene banks of gonococci and chlamydia which are being screened for the producion of surface proteins. We have also characterized the genome of Borrelia hermsii with regard to G plus C content, genome size, and plasmid DNA content. One or more of the 5 plasmids in B. hermsii appears to be lost during cultivation in vitro.